This invention relates to an improved method of manufacturing alkylene oxide adducts of an aliphatic alcohol, said alcohol having been obtained by the liquid phase oxidation of a saturated aliphalic hydrocarbon having 8 to 20 carbon atoms in the presence of a boron compound by contacting with a molecular oxygen containing gas.
In the addition reaction of alkylene oxides to alcohols in the presence of an acid catalyst, it is known that the conversion of alcohols must be to an extent of 30 to 80 % from the economic point of view, so that it is necessary to recover unreacted alcohols by means of, e.g., distillation, and to recycle the recovered alcohols to the reaction system.
Not only alcohols obtained by the oxidation of hydrocarbons but alcohols in general may contain impurities, e.g. carbonyl compounds and hydrocarbons, which do not react with alkylene oxide. Such impurities are accumulated in the system with the recycle of recovered alcohols and this makes it difficult to obtain a product of a uniform quality by continuing the reaction under the same conditions. As the reaction is continued or repeated, the content of the impurities gradually increases and, with this, the average number of moles of added alkylene oxide (it will hereinafter be referred to as n.) per mole of alcohol in the product gradually varies. Therefore, it is necessary in order to obtain a product of a uniform quality to continually adjust the feed rate of fresh alcohol and/or alkylene oxide and to vary the material balance in the separation step of unreacted alcohol and of impurities by means of, e.g., distillation. Unfortunately, it is difficult to completely separate the impurities, because of the relationship of their boiling points to that of the alcohol and the accumulated impurities at last make it impractical to recycle the recovered alcohol.
If the impurities contained in raw alcohols are simple carbonyl compounds or olefinic compounds hydrotreating may be employed in the purification step. Such a treatment has been utilyzed in practical to improve color and odor of the products but is ineffective for the complete removal of impurities contained in raw alcohols, e.g. hydrocarbons.
Therefore, there is a need for an improved method of manufacturing alkylene oxide adducts of aliphatic alcohols having uniform good quality in which removal of accumulated impurities is attained economically and efficiently.
An object of the present invention is to provide an improved method of manufacturing alkylene oxide adducts of aliphatic alcohols having uniform good quality in which removal of accumulated impurities is attained economically and effectively.